Wireless communications devices are an integral part of society and permeate daily life. The typical wireless communications device includes an antenna, and a transceiver coupled to the antenna. The transceiver and the antenna cooperate to transmit and receive communications signals. A typical radio frequency (RF) transceiver includes a power amplifier for amplifying low amplitude signals for transmission via the antenna.
In some communications devices, the RF transceiver operates at multiple frequency bands, i.e. a multi-band communications device. Accordingly, the multi-band communications device may include a switch between the antenna and the RF transceiver for routing the appropriate signal through frequency band specific circuitry, such as power amplifiers and filters. In certain high power applications, diode switches may be used for the switch. In one approach, the diode switches comprise PIN (i.e. a diode with a wide, undoped intrinsic semiconductor region between a p-type semiconductor and an n-type semiconductor region) diodes in a series-shunt configuration.
A series-shunt configuration of PIN diode switches is typically used to achieve a relatively high isolation, which may be important in high frequency applications, for example greater than 1 GHz. To achieve relatively high isolation in the high power application, for example, greater than 10 W, a relatively high reverse bias voltage is used. The series diode and shunt diode of a particular switched path must be forward and reversed biased complementarily to minimize insertion loss and maximize isolation. Packaged series-shunt PIN diode switches may provide increased thermal performance and higher isolation.